1. Field of the Invention
The present invention relates to a directional control valve which makes it possible to control the flow direction of a pressure fluid.
2. Description of the Related Art
The directional control valve has been hitherto used in order to control the flow direction of the pressure fluid. Such a directional control valve includes, for example, a three-port solenoid-operated valve for operating a valve plug with a solenoid.
The three-port solenoid-operated valve has three ports including a pressure fluid supply port, an output port, and a discharge port. The pressure fluid supply port and the output port are formed coaxially respectively via a communication passage on opposing side surface portions of a casing. The discharge port is formed in a direction substantially perpendicular to an axis obtained by connecting the pressure fluid supply port and the output port. The valve plug for opening/closing the communication passage in accordance with the displacement action of the valve plug is arranged between the pressure fluid supply port and the output port. When the valve plug is separated from a seat section to open the communication passage, the pressure fluid supply port communicates with the output port.
In this-arrangement, for example, in the case of the solenoid-operated valve of the normally closed type, the output port communicates with the discharge port when the valve plug is seated on the seat section to give the valve-closed state. On the other hand, when the valve plug is separated from the seat section to give the valve-open state by attracting the valve plug in accordance with the electric power-applying action on the solenoid, the pressure fluid supply port communicates with the output port. As described above, in the case of the normally closed type solenoid-operated valve, the switching operation is performed between the communication state of the output port and the discharge port during no electric power application to the solenoid and the communication state of the pressure fluid supply port and the output port during the electric power application to the solenoid.
However, in the case of the three-port solenoid-operated valve concerning the conventional technique described above, it is necessary that the valve plug and the solenoid for attracting the valve plug are arranged between the pressure fluid supply port and the output port. Both ports are arranged mutually opposingly. Therefore, an inconvenience arises in that it is impossible to suppress the widthwise dimension along the connection of the pressure fluid supply port and the output port.